Silicon is one example of a composition that is essentially non-electrically conductive in the solid state and electrically conductive in the liquid (molten) state. For example the electrical (specific) conductivity, κ, of pure (semiconductor grade) silicon can be expressed mathematically as:
                              log          ⁡                      (            κ            )                          =                  (                      4.247            -                          (                              2924                T                            )                                )                                    [                  Eq          .                                          ⁢                      (            1            )                          ]            
where κ is measured in siemens per meter and the temperature of the silicon, T, is measured in kelvin. Therefore pure silicon is generally considered an electrical insulator at less than 700 kelvin (427° C.) and an electrical conductor at a much higher temperature that is above its nominal melting temperature of 1683 kelvin (1410° C.).
Electric induction power can be used with susceptor furnaces to heat and melt materials that are supplied as charge to the furnace when the charge is in the substantially solid, non-electrically conductive state, and electrically conductive in the liquid (or molten) state.
It is one object of the present invention to provide apparatus and method for heating and melting a material that is essentially non-electrically conductive in the solid state, and electrically conductive in the liquid (or molten) state by electric induction power while enhancing rapid removals of impurities from the material by reactive degasification of the material when it is in the molten state.